A positioning method using GPS satellites, as typified by car navigation, is widely used and high precision location detection is realized. However, in indoor or shadowed places, because it is unable to receive signals from GPS satellites, location detection using GPS satellites cannot be performed. For cars, because most routes they run are outside, time during which they run through a shadowed place is short and location detection only becomes impossible transiently. On the other hand, walkers often move indoors or underground and it is difficult to continuously detect the location of a walker solely by GPS. Therefore, in indoor or underground places, it is needed to detect the location of a walker using a positioning technique other than GPS.
In this respect, for instance, as set forth in Japanese Unexamined Patent Application Publication No. 2011-237452, there is a technique that analyzes which speed and in which direction a walker is moving using data acquired by various sensors such as an acceleration sensor and a gyro sensor and infers the location of the walker. This technique makes it possible to detect the location of a walker even in a building.